You can use relays and wire them so that the block switches are bypassed when you are using DCC. Then all you need are single throw switches for each block, and you don't have to worry about flipping a switch to 'DCC,' you flip one switch and all blocks go to DCC mode.
Am I making sense? If you want, I can draw out a schematic of what I have in mind. It would also let you use those nifty DCC breakers Digitrax makes.